Heating/ventilating/air conditioning systems for vehicles

ABSTRACT

An HVAC Integrated electronic Module (HIM) ( 41 ) for controlling airflow through an HVAC module ( 12 ), the HVAC module including a variable speed blower motor ( 18 ), a plurality of airflow doors ( 26–28 ) for controlling air direction and hot-cold air temperature blend, and electrical actuators, servo motors or stepper motors for said doors, the HIM including: one or more air temperature sensors ( 22 ) for measurement of one or more of intake air temperature, outlet air temperature, air-off evaporator temperature and engine coolant temperature; actuator control circuitry ( 31 ) for controlling said electrical actuators, servo motors or stepper motors; blower motor speed control circuitry ( 15 ) for speed control of the variable speed blower motor; sensor control circuitry for said sensors; and communication circuitry for a serial communication interface ( 42 ) to enable communication with a vehicle users interface ( 32 ).

This Application is a Section 371 National Stage Application ofInternational Application No. PCT/AU01/00174 filed 21 Feb. 2001 andpublished as WO 01/62529 on 31 Aug. 2001 in English.

This invention relates to improvements in heating/ventilation/airconditioning systems (HVAC) in vehicles, particularly motor vehicles,and relates particularly to an improved method of controlling theairflow and temperature through the HVAC module by integration of thecontrolling devices into a HVAC Integrated electronic Module (HIM)controlled by a serial communication bus.

Current technology in HVAC generally comprises a user interface (ClimateControl) by which the driver or passenger controls the airflow, and aHVAC module which directs airflow from one or more inlet points, throughheater cores and/or evaporator cores and onto a number of outlets. TheClimate Control may comprise a dedicated user interface for controllingthe HVAC system or it may be integrated into a Central Control anddisplay together with other vehicle functions. The airflow through theHVAC module is generally controlled by airflow doors to open, close orblend the air through various passages through the HVAC module. Airflowdoors may comprise Butterfly doors, Clamshell doors or roller vanes.

The Climate Control may connect to the HVAC module either by anelectrical control system or by a mechanical linkage or a combination ofboth. Where the UVAC module is electrically controlled, electricalactuators, servo motors or stepper motors are used for movement of theHVAC module airflow doors. The airflow speed is generally controlled byvarying the voltage across an electrical motor with airflow impeller(blower motor) by the use of electrical resistors or by a semiconductor(speed control unit). The speed control unit is controlled, in turn, bythe Climate Control. In a typical HVAC module, one or more of theelectrical actuators, servo motors or stepper motors may be used tocontrol the cold to hot air temperature blend (air mix) while otherelectrical actuators, servo motors or stepper motors are used to controlthe outlet airflow directions (mode), while other electrical actuators,servo motors or stepper motors are used to control the inlet airflowdirection (intake). In a typical HVAC module there will be a variety ofair temperature sensors for such measurements as intake air temperature,outlet air temperature, air-off evaporator temperature and enginecoolant temperature. In a typical HVAC module there will also be avariety of other electrical devices such as pressure sensors, humiditysensors, air quality sensors, air filter sensors (both pressure orinfrared) and positional sensors.

While current technology is relatively sophisticated, it is stillnecessary to connect the HVAC module to the other vehicle systems andthe Climate Control generally by employing a wiring harness forconducting electrical signals from the Climate Control to the HVACmodule. Consequently, a large plurality of wires and associatedconnectors are required in wiring the Climate Control to the HVACmodule.

Further, with current systems, different wiring harnesses are requiredwhere different HVAC module functionality or features are offeredthrough a vehicle model range.

It is therefore desirable to provide an improved HVAC system thatobviates at least some of the disadvantages of the current HVAC systems.

It is also desirable to provide an improved HVAC system that will beeconomical to manufacture, install, validate and service.

It is also desirable to provide an improved HVAC module that providesincreased functionality and features.

It is also desirable to provide a HVAC module that can be adapted for avariety of functional needs.

It is also desirable to reduce the electrical wiring on and associatedwith the HVAC module and system.

In accordance with one aspect of the invention there is provided an HVACIntegrated electronic Module (HIM) for controlling airflow through anHVAC module, the HVAC module including a variable speed blower motor, aplurality of airflow doors for controlling air direction and hot-coldair temperature blend, and electrical actuators, servo motors or steppermotors for said doors, the HIM including:

one or more air temperature sensors for measurement of one or more ofintake air temperature, outlet air temperature, air-off evaporatortemperature and engine coolant temperature;

actuator control circuitry for controlling said electrical actuators,servo motors or stepper motors;

blower motor speed control circuitry for speed control of the variablespeed blower motor;

sensor control circuitry for said sensors; and

communication circuitry for a serial communication interface to enablecommunication with a vehicle users interface.

Preferably, the HIM also includes electrical devices for sensinghumidity, air quality, air filter condition (both pressure or infrared)and position, as well as control circuitry for said electrical devices.

By redesigning the HVAC module to incorporate at least a significantportion of the control circuitry which would otherwise be incorporatedin the vehicle user interface, or Climate Control, or each individualelectrical device mounted to the HVAC module and by communicating usinga serial communication bus, substantially reduced electrical wiring isrequired from the Climate Control to the HVAC module, and it is nolonger necessary to have a separate HVAC module sub-wiring harnessassembly connecting the actuators, blower motor speed control unit, airtemperature sensors and various other electrical devices to the ClimateControl.

Further, because according to this invention, at least a significantportion of the all control circuitry is now located in the IntegratedHVAC electronic Module (HIM), a greater degree of testing can occur onthe HVAC module prior to assembly in the vehicle and, once in thevehicle, a greater degree of testing can occur to the HVAC system priorto assembly of the instrument panel in the vehicle. Still further, withthe integration of circuitry and mechanisms with the HIM a greaterdegree of functionality is possible such as blower speed compensationwith road speed, blower speed compensation with air modes or temperatureblend, blower speed compensation during changes of air modes to preventair bursts, intake air bleed compensation for optimising HVAC systemperformance, ram air compensation with vehicle speed, blower speedcompensation with battery voltage, compensation for non-linearity's ofhot-cold temperature air mix door position versus outlet temperature,and the like.

Further, the invention control circuitry may either be implemented byapplication of a microprocessor based control system or discreteelectronic components. In the case of a microprocessor based controlsystem and with input of outside air temperature and sunloadmeasurements, either discretely or on serial communication bus, the HVACIntegrated electronic Module (HIM) may also incorporate climate controlcircuitry implementing an Automatic Climate Control (ACC) strategy.

Further, the HVAC Integrated electronic Module (HIM) may use a sharedserial communication bus with other electronic modules in the vehicle toenable shared data between said electronic modules and the HIM and alsoenable the HIM to have diagnostic interrogation through a single pointvehicle diagnostic connection.

In order that the invention is more readily understood, an embodimentthereof will now be described with reference to the accompanyingdrawings therein:

FIG. 1 is a diagrammatic view of an HVAC unit in accordance with oneembodiment of the invention;

FIG. 2 is a schematic wiring diagram illustrating the wiring system of aprior art HVAC unit; and

FIG. 3 is a schematic wiring diagram illustration the wiring system foran HVAC unit in accordance with the present invention.

Referring to the drawings, an HVAC module comprises a mechanical system,diagrammatically shown in FIG. 1, which incorporates a plurality ofdoors to direct airflow from the intake to the outlets. The air intake14 draws air from outside the vehicle cabin (fresh air) while air intake16 draws airflow from within the vehicle cabin (recirculated air). Anair intake door 17 is movable by an electrical actuator, servo motor orstepper motor (not shown) to vary the blend of fresh and recirculatedair.

A blower motor 18 is used to push air through the HVAC module 12. Theblower motor is controlled by a speed control unit 15 that uses airflowthrough the HVAC module to dissipate heat. An evaporator core 21 is usedto reduce the air temperature as air flows through its fins. A heatercore (not shown) is similarly used to increase air temperature as airflows through its fins. An air mix door is used to vary the blend of hotair (that which has flowed through the heater core) with cold air (thatwhich has flowed through the evaporator core 21) and is controlled inposition by an electrical actuator, servo motor or stepper motor.Various mode doors are used to direct airflow to various outlets usuallycomprising screen 26, face 27 and foot 28 or any combination thereof.The electrical actuators, servo motors and stepper motors for moving thedoors are well known in the art and do not need to be described indetail.

Various temperature sensors, on of which is shown at 30, are used atvarious positions throughout the HVAC module to measure air temperaturesfor particular climate control strategies. Various electrical devices(not shown) such as pressure sensors, humidity sensors, air qualitysensors, air filter sensors 44 (either or both pressure or infrared airfilter sensors are represented by block 44 in FIG. 3) and positionalsensors are also used at various locations on the HVAC module forparticular climate control strategies. The use of temperature sensors,pressure sensors and other electrical devices is generally known in theart.

In accordance with the present invention, some or all of theseelectrical or electro-mechanical devices are integrated into a singleHVAC Integrated electronic Module (HIM) 41 (FIG. 3). The HVAC Integratedelectronic Module (HIM) incorporates electronic control circuitry 31 forthe various electrical actuators, servo motors or stepper motors, thevarious temperature sensors, the blower motor speed control unit and thevarious electrical devices such as pressure sensors, humidity sensors,air quality sensors, air filter sensors (both pressure or infrared) andpositional sensors.

As shown in FIG. 2, in prior art HVAC module, the control of the variousfunctions are effected from the vehicle user interface or ClimateControl 32. The Climate Control 32 then controls the various electricalactuators, servo motors or stepper motors on the HVAC module 40 by meansof a plurality of individual electrical wires 36 each related to aparticular function, operational mode or airflow speed. Thus, the priorart HVAC module 40 illustrated has an air-off temperature sensor 22, anair mix motor 34, mode outlet motor 33, recirculate motor 35 and blowermotor 19 each connected by a plurality of wires 36 to the ClimateControl 32 for power supply and functional control. These electricalwires 36 include five (5) high current wires for the blower motor 19. Awiring harness and associated connectors for twenty two (22) separatewiring connections is therefore required for the HVAC module 12 toconnect the module to the Climate Control 32 and the vehicle wiringsystem 37.

As shown in FIG. 3, in accordance with the present invention, theintegration of the control circuitry 31 into the HVAC Integratedelectronic Module (HIM) 41, and the use of a serial communication bus42, reduces the number of control electrical wires 36. In the embodimentillustrated in FIG. 3, with the same components as in the prior artmodule, only five (5) wires are required for power and communicationwith the user interface or Climate Control 32, and only two (2) of theseare high current wires. The HVAC serial bus signals:

-   -   A/C Switch    -   A/C Request    -   A/C Thermister    -   Blower Speed    -   Recirculate control    -   Air direction control    -   Temperature control

With the system of the present invention, internal fault detection mayalso be achieved as a feature of the control circuitry 31. A diagnosticconnector 38 may plug into the serial communication bus 42 to enabletesting and diagnostic equipment to interrogate the HIM 41 module in theevent of faults or reprogramming requirements. In accordance with thepresent invention various additional functional features can be appliedto the control circuitry 31 without the need to make changes to thewiring harnesses, vehicle electrical hardware or mechanical hardware.For example, the number of operational modes may be increased ordecreased or varied to provide more, less or different positions of aircontrol doors without the need to change wiring.

Many other modifications may be made in the design and or constructionof an HVAC Integrated electronic Module (HIM) in accordance with thepresent invention and all such modifications which come within the scopeof the invention shall be deemed to be within the ambit of the abovedescription.

1. A control module for controlling airflow through an HVAC module of avehicle, the control module including at least the following electricalor electromechanical components, integrated into a single housing: oneor more temperature sensors for measurement of one or more of intake airtemperature, outlet air temperature, air-off evaporator temperature andengine coolant temperature; at least one electrical actuator, servomotor or stepper motor actuator control circuitry for controlling saidat least one electrical actuator, servo motor or stepper motor; blowermotor speed control circuitry for speed control of the variable speedblower motor of the HVAC module; sensor control circuitry for saidsensors; and communication circuitry for a serial communicationinterface to enable communication with a vehicle users interface.
 2. Thecontrol module according to claim 1, and further including: one or moreelectrical devices for sensing one or more of pressure, humidity, airquality, air filter condition and position; and electrical devicecontrol circuitry for said electrical sensing devices.
 3. The controlmodule according to claim 2, wherein said one or more electrical devicesfor sensing air filter condition use either or both of infra-red orpressure sensing.
 4. The control module according to claim 1, whereinthe control circuitry is implemented by application of a microprocessorbased control system.
 5. The control module according to claim 4, andfurther including climate control circuitry implementing an AutomaticClimate Control (ACC) strategy based upon measurement of outside airtemperature and sun-load measurements, either discretely or on saidserial communication interface.
 6. The control module according to claim1, wherein the control circuitry is implemented by application ofdiscrete electronic components.
 7. The control module according to claim1, wherein the serial communication interface is adapted to be sharedwith other electronic modules in the vehicle to enable data to be sharedbetween said other electronic modules and the HIM and also enablediagnostic interrogation to be performed on the HIM through a singlepoint vehicle diagnostic connection.
 8. The control module of claim 1,wherein electrical connections between said components are independentof an electrical wiring system of a vehicle too which the control moduleis to be fitted.
 9. The control module of claim 8, wherein electricalconnections between said components form part of the control module. 10.The control module of claim 9, wherein electrical connections betweensaid components include one or more of the following electricalconnection means; a printed circuit board, a dedicated wiring harness.11. A control module for controlling airflow through an HVAC module of avehicle, said control module including at least the following electricalor electromechanical components mechanically integrated into a singlehousing: one or more temperature sensors for measurement of one or moreof intake air temperature, outlet air temperature, air-off evaporatortemperature, air-off evaporator temperature and engine coolanttemperature; actuator control circuitry for controlling said at leastone electrical actuator, servo motor or stepper motor of the HVACmodule; blower motor speed control circuitry for speed control of avariable speed blower motor of the HVAC module; sensor control circuitryfor a serial communication interface to enable communication with avehicle users interface.